Structure and properties of a polymeric binder based on (meth)acrylate copolymers for photochromic compositions

The methods of absorption spectroscopy, dielectric relaxation, thermomechanics, atomic force microscopy, and X-ray diffraction analysis were used to characterize the physical properties and structure of methyl methacrylate copolymers with 2-ethylhexyl acrylate and octyl methacrylate. It was demonstrated that methyl methacrylate-octyl methacrylate copolymers within a wide composition range possess an optical transparency at the same level as that of poly(methyl methacrylate) but have a larger free volume. The enthalpies of interaction between photochromic compounds of the spiropyran class and a polymeric binder based on the resultant copolymers were determined indicating the absence of specific interaction between the system components. The rates of photochromic transformations of spiropyran molecules in (co)polymeric matrices were studied; they were found to significantly depend on the composition and structure of the copolymer.